As the valve timing control device configured in the way heretofore described, WO2011/055589 (Reference 1) is such that a plurality of fluid pressure chambers are formed on the inner periphery side of the drive side rotating member, the driven side rotating member is fitted inside thereof, and the fluid pressure chambers are partitioned by respective vanes provided protruding from the outer surface of the driven side rotating member, thereby forming advanced angle chambers and retarded angle chambers. Also, this configuration includes an intermediate lock mechanism which constrains the relative rotation phase of the drive side rotating member and driven side rotating member to an intermediate lock phase which is an intermediate phase between a most advanced angle and a most retarded angle, and a most retarded angle lock mechanism which constrains the relative rotation phase to a most retarded angle phase in which the relative rotation phase is at the most retarded angle.
In WO2011/055589 (Reference 1), the intermediate lock mechanism includes a groove-shaped intermediate lock groove formed in the outer periphery of the driven side rotating member and a pair of intermediate lock members provided so as to be advanceable into and withdrawable from the drive side rotating member, in which the relative rotation phase is constrained to the intermediate lock phase by simultaneously retaining both the intermediate lock members one in each end of the intermediate lock groove. Also, the most retarded angle lock mechanism includes, apart from the intermediate lock mechanism, a most retarded angle lock groove formed in the outer periphery of the driven side rotating member and a most retarded angle lock member provided so as to be advanceable into and withdrawable from the drive side rotating member, in which the relative rotation phase is constrained to the most retarded angle phase by the most retarded angle lock member being retained in the most retarded angle lock groove.
As the valve timing control device configured in the way heretofore described, a lock mechanism which constrains the relative rotation phase to the most retarded angle and a phase shift limiting mechanism which allows the relative rotation phase to shift within a set allowable range are described in JP 2007-198365A (Reference 2). In JP 2007-198365A (Reference 2), when the condition of an engine, such as temperature, satisfies certain conditions, the engine is started with the relative rotation phase set to the most retarded angle by the lock mechanism.
In JP 2007-198365A (Reference 2), when starting the engine, a lock member of the lock mechanism is in a lock state by being inserted in an engagement depression portion, and an advanceable/withdrawable member of the phase shift limiting mechanism is in a condition in which it is inserted in a limiting depression portion. A configuration is adopted such that after a start of cranking, hydraulic oil is supplied to advanced angle control oil passages and lock passages, thus releasing a lock of the lock mechanism, after which the relative rotation phase is shifted in an advanced angle direction to hold the advanceable/withdrawable member in abutment with an end portion of the limiting depression portion, and it is thereby possible to set the relative rotation phase to the intermediate phase.
As described in WO2011/055589 (Reference 1), in order to provide the pair of intermediate lock members, spaces in which to dispose them are necessary. This causes an adverse effect, such as a reduction in the volume of oil chambers formed in the drive side rotating member or a reduction in the number of oil chambers. Three oil chambers are shown in the drawings of WO2011/055589 (Reference 1). However, in order to obtain high relative torque, it is desired to obtain a strong shift force (high relative torque) without increasing the pressure of hydraulic oil by increasing the number of oil chambers and increasing the number of vanes.
In order to improve the startability of the internal combustion engine and reduce a toxic substance, such as hydrocarbon, contained in an exhaust gas, it is necessary to set a relative rotation phase when starting the internal combustion engine to the most retarded angle, or set the relative rotation phase to the intermediate phase, based on the temperature of combustion chambers of the internal combustion engine. Also, when considering the configuration of constraining the relative rotation phase to the intermediate phase and most retarded angle phase, it is desirable to firmly constrain the relative rotation phase to each phase. Consequently, with a configuration in which it is necessary to continue supplying hydraulic oil to the advanced angle chambers in order to maintain the relative rotation phase in the intermediate rotation phase, as with the configuration described in JP 2007-198365A (Reference 2), it may happen that the relative rotation phase varies, and improvement is demanded.
A need thus exists for a valve timing control device which is not susceptible to the drawback mentioned above.